Wearable temperature sensors are becoming increasingly important for continuous health monitoring, personalized healthcare, and biointegrated electronic systems. However, conventional temperature-sensing platforms often suffer from limited thermal sensitivity, insufficient mechanical compliance, and unstable performance under repeated deformation, making it difficult to detect subtle physiological temperature variations in real time. Here, this tutorial status report presents a fabrication strategy for highly sensitive wearable temperature sensors based on gold-doped crystalline silicon nanomembranes. Gold diffusion into crystalline silicon introduces deep-level impurity states that modulate the Fermi level and shift the freeze-out region toward the physiological temperature range, enabling an ultrahigh negative temperature coefficient of resistance. By integrating the gold-doped silicon nanomembrane with a polyimide-supported ultrathin platform, neutral mechanical plane design, and serpentine mesh interconnects, the resulting device can provide high thermal sensitivity, fast response, conformal skin attachment, and stable operation under mechanical deformation. This fabrication approach is expected to broaden the use of impurity-engineered silicon nanomembranes in next-generation wearable sensors, flexible bioelectronics, and multifunctional healthcare monitoring systems.
MoS₂ has attracted significant attention as a next-generation semiconductor material to overcome the physical scaling limits of silicon-based devices due to its atomic thinness and excellent electrical properties. However, high contact resistance and the formation of Schottky barriers resulting from interface defects during the metal deposition process remain major bottlenecks that degrade overall device performance and reliability. In this study, we fabricated MoS₂ FETs by employing Sb₂Te₃, van der Waals (vdW) contacts. Minimized interface inhomogeneity was achieved through a hemispherical stamp-based dry transfer of h-BN for device encapsulation. h-BN encapsulation decreased the hysteresis window in the ±25 V gate voltage range from 17 V to 11.5 V compared to un-capped devices, confirming that charge trapping phenomena induced by external environmental factors were suppressed. Consequently, the dry transfer technique of h-BN using a hemispherical stamp demonstrated in this study provides a potential solution for securing the long-term reliability of MoS₂ devices with vdW contact by minimizing interface contamination.
Micro-LEDs, which have a chip size of less than 100 × 100 μm², have been potential candidates for conventional LCDs and OLEDs due to their high optical power, outstanding stability, and nanosecond response time. However, Micro-LED chips are fabricated only on limited substrates due to the high-temperature metal-organic chemical vapor deposition process and lattice-mismatch issues. Therefore, the fabrication of Micro-LED displays requires complex processes such as chip fabrication, transfer, bonding, and repair. Especially, Micro-LED transfer and bonding have been critical challenges for the Micro-LED display commercialization. Here, recent advances in the transfer and bonding of Micro-LEDs are introduced, and novel Micro- LED display fabrication methods are reviewed to provide a practical outlook for both mass production and commercialization of Micro-LED displays.
In this study, the electrical properties of zinc oxide (ZnO) thin-film transistors (TFTs) based on oxide semiconductors were analyzed. As interest in next-generation transparent and flexible displays grows, ZnO, which offers high field-effect mobility and transparency, has emerged as a promising material to overcome the limitations of amorphous silicon (a-Si)-based TFTs. ZnO has a wide bandgap and optical transparency and can be deposited on various substrates at low temperatures, making it a suitable channel material for future display devices. In this study, ZnO TFTs were fabricated with an inverted staggered structure using a p++ Si wafer coated with SiO2 as the substrate. The ZnO channel layer was deposited by RF magnetron sputtering, and the ITO source/drain electrodes were formed using an e-beam evaporator. The electrical characteristics was evaluated using Keithley 4200A-SCS parameter analyzer. Mobility, On/Off ratio, and subthreshold swing (SS) were calculated from the measurements.
With the recent development of emerging technologies, information acquisition and delivery between users has been actively conducted, and inorganic thin film transfer technology that effectively transfers various materials and devices is being studied to develop flexible electronic devices accordingly. This is aimed at innovative structural changes and functional improvement of electronic devices in the era of the Internet of Things (IoT). In particular, advanced technologies such as micro- LEDs are used to realize high-resolution flexible displays, and the possibility of heterogeneous integrated technologies can be presented by precisely transferring materials to substrates through various transfer process. This paper introduced physical, chemical, and self-assembly transfer methods based on inorganic thin film materials to implement heterogeneous integrated flexible semiconductor systems and introduces the results of application studies of semiconductor devices obtained through different transfer technologies. These studies are expected to bring about innovative changes in the field of smart devices, medical technology, and user interfaces in the future.
Micro light-emitting diodes (LEDs), with a chip size of 100 micrometers or less, have attracted significant attention in flexible displays, augmented reality/virtual reality (AR/VR), and bio-medical applications as next-generation light sources due to their outstanding electrical, optical, and mechanical performance. In the realm of bio-medical devices, it is crucial to transfer tiny micro LED chips onto desired flexible substrates with low precision errors, high speed, and high yield for practical applications on various parts of the human body, including someone’s face and organs. This paper aims to introduce a fabrication process for flexible micro LED devices and propose micro LED transfer techniques for cosmetic and medical applications. Flexible micro LED technology holds promise for treating skin disorders, cancers, and neurological diseases.
For the past several decades, various next-generation patterning methods have been developed to obtain well-designed nano-to-micro structures, such as imprint lithography, nanotransfer printing (nTP), directed self-assembly (DSA), E-beam lithography, and so on. Especially, nTP process has much attention due to its low processing cost, short processing time, and good compatibility with other patterning techniques in achieving the formation of high-resolution functional patterns. To transfer functional patterns onto desirable substrates, the use of soft materials is required for precise replication of master mold. Here, we introduce a simple and practical nTP method to create highly ordered structures using various polymeric replica materials. We found that polymethyl methacrylate (PMMA), polystyrene (PS), and polyvinylpyridine (PVP) are possible candidates for replica materials for reliable duplication of Si master mold based on systematic analysis of pattern visualization. Furthermore, we successfully obtained well-defined metal and oxide nanostructures with functionality on target substrates by using replica patterns, through deposition and transfer process. We expect that the several candidates of replica materials can be exploited for effective nanofabrication of complex electronic devices.
In this study, we fabricated multilayer graphene on a glass substrate by stacking the monolayer graphene synthesized via chemical vapor deposition. The electrical sheet resistance and optical transmittance were evaluated to confirm the quality of the stacked multilayer graphene. Using the fabricated multilayer graphene/glass structure, we characterized its thermal radiative property in terms of the integrated emissivity. The integrated emissivity of the multilayer graphene/glass structure was tuned from 0.91 to 0.72 when the number of graphene layers was changed from 1 to 12. We also demonstrated that the emissivity tunability provided a way to control the apparent temperature of an object that can be used in infrared stealth applications.
In order to fabricate high-quality SiC substrates for power electronic devices, various single crystal growing methods were prepared. These include the physical vapor transport (PVT) and top seeded solution growth (TSSG) methods. All the suggested SiC growth methods generally use induction-heating furnaces. The temperature distribution in this system can be easily adjusted by changing the hot-zone design. Moreover, precise temperature control in the induction-heating furnace is favorably required to grow a high-quality crystal. Therefore, in this study, we analyzed the heat transfer in these furnaces to grow SiC crystals. As the growth temperature of SiC crystals is very high, we evaluated the effect of radiation heat transfer on the temperature distribution in induction-heating furnaces. Based on our simulation results, a heat transfer strategy that controls the radiation heat transfer was suggested to obtain the optimal temperature distribution in the PVT and TSSG methods.
This study discusses and demonstrates the structural stability of highly ordered Pt patterns formed on a transparent and flexible substrate through the process of nanotransfer printing (nTP). Bending tests comprising approximately 1,000 cycles were conducted for observing Pt line patterns with a width of 1 μm formed along the direction of the horizontal (x-axis) and vertical (y-axis) axes (15 mm × 15 mm); and adhesion tests were performed with an ultrasonicator for a period greater than ten minutes, to analyze the Pt crossbar patterns. The durability of both types of patterns was systematically analyzed by employing various microscopes. The results show that the Pt line and Pt crossbar patterns obtained through nTP are structurally stable and do not exhibit any cracks, breaks, or damages. These results corroborate that nTP is a promising nanotechnology that can be applied to flexible electronic devices. Furthermore, the multiple patterns obtained through nTP can improve the working performance of flexible devices by providing excellent structural stability.
MOS-FET structured gas sensors were manufactured using MWCNTs for application as NOx gas sensors. As the gas sensors need to be heated to facilitate desorption of the gas molecules, heat dispersion plays a key role in boosting the degree of uniformity of molecular desorption. We report the desorption of gas molecules from the sensor at 150℃ for different sensor electrode gaps (30, 60, and 90 μm). The COMSOL analysis program was used to verify the process of heat dispersion. For heat analysis, structure of FET gas sensor modeling was proceeded. In addition, a property value of the material was used for two-dimensional modeling. To ascertain the degree of heat dispersion by FEM, the governing equations were presented as partial differential equations. The heat analysis revealed that although a large electrode gap is advantageous for effective gas adsorption, consideration of the heat dispersion gradient indicated that the optimal electrode gap for the sensor is 60 μm.
Current progress in the development of semiconductor technology in applications involving high electron mobility transistors (HEMT) and power devices is hindered by the lack of adequate ways todissipate heat generated during device operation. Concurrently, electronic devices that use gallium nitride (GaN) substrates do not perform well, because of the poor heat dissipation of the substrate. Suggested alternatives for overcoming these limitations include integration of high thermal conductivity material like diamond near the active device areas. This study will address a critical development in the art of GaN on diamond (GOD) structure by designing for ideal heat dissipation, in order to create apathway with the least thermal resistance and to improve the overall ease of integrating diamond heat spreaders into future electronic devices. This research has been carried out by means of heat transfer simulation, which has been successfully demonstrated by a finite-element method.
Generally, MWCNT, with thermal, chemical and electrical superiority, is manufactured with CVD (Chemical Vapor Deposition). Using MWCNT, it is comonly used as gas sensor of MOS-FET structure. In this study, in order to repeatedly detect gases, the author had to effectively eliminate gases absorbed in a MWCNT sensor. So as to eliminate gases absorbed in a MWCNT sesor, the sensor was applied heat of 423[K], and in order to observe how the applied heat was diffused within the sensor, the author interpreted the diffusion process of heat, using COMSOL interpretation program. In order to interpret the diffusion process of heat, the author progressed modeling with the structure of MWCNT gas sensor in 2-dimension, and defining heat transfer velocity(u=△T/△χ), accorded to governing equation within the sensor, the author proposed heat transfer mechanism.
We have investigated the effects of spacer layer inserted between blue and red doped emissionlayers on the emission and efficiency characteristics of phosphorescent OLEDs. N,N``-di-carbazolyl-3,5-benzene(mCP) was used as a host layer. Iridium(III)bis[(4,6-di-fluorophenyl)- pyridinato-N,C2``]picolinate (FIrpic) andtris(1-phenyl-isoquinolinato-C2,N)iridium(III) [Ir(piq)3] were used as blue and red dopants, respectively. Theemission layer structure was mCP (1-x) nm/mCP:Ir(piq)3 (5 nm, 10%)/mCP (x nm)/mCP:FIrpic (5 nm, 10%). The thickness of mCP spacer layer was varied from 0 to 15 nm. The emission from Ir(piq)3 and theefficiency of the device were dominated by energy transfer from mCP host and FIrpic molecules, and bydiffusion of mCP host triplet excitons.
Based on both organic synthesis and theoretical calculations on the effects of molecular orbital energy levels of amines on the of fluorescence properties of the fluorophore, fluorescent "turn-on" chemosensors detecting hazardous substances, including aldehyde chemicals and Hg2 ion, were developed.
Ordered mesoporous oxide films have been focused because of their low density, high interior specific surface area, and high thermal insulation. Specially, the ordered mesoporous oxide films prepared by self-assembly has many advantages due to easy process and high reproducibility. In this work, ordered mesoporous SiO2, Al2O3, and TiO2 films were synthesized by control of composition and processing parameter. Also, their structural, thermal, and mechanical properties were characterized variously. In conclusion, ordered mesoporous oxides will be one of core materials in new technology due to their excellent and unique properties.